Clever surgery turns an ankle into a ‘knee’

While limb-sparing surgery for bone cancer is becoming more common, very young children with bone cancer face significant challenges and have limited surgical options. A page in the August 19 electronic issue of the New England Journal of Medicine illustrates the case of a five-year-old girl with Ewing’s sarcoma, a cancerous tumor, behind her left knee. Surgeons at The Children’s Hospital of Philadelphia used a limb-sparing technique called rotationplasty to remove the diseased portion of bone, turn the shortened portion of the leg bone in a half-circle and reattach it, with the ankle joint functioning as a knee. With a prosthetic attached to the mobile joint, the child, now 13, enjoys gymnastics and cheerleading.

While limb-sparing surgery for bone cancer is becoming more common, very young children with bone cancer face significant challenges and have limited surgical options.

A page in the August 19 electronic issue of the New England Journal of Medicine illustrates the case of a five-year-old girl with Ewing’s sarcoma, a cancerous tumor, behind her left knee. Surgeons at The Children’s Hospital of Philadelphia used a limb-sparing technique called rotationplasty to remove the diseased portion of bone, turn the shortened portion of the leg bone in a half-circle and reattach it, with the ankle joint functioning as a knee. With a prosthetic attached to the mobile joint, the child, now 13, enjoys gymnastics and cheerleading.

”For very young children with cancer above the knee, one option is rotationplasty. This procedure removes the involved bone and replaces the knee joint with the ankle joint; to do this, surgeons rotate the leg halfway around before reattaching it. By moving up the ankle and reattaching it to where the knee joint was, we can preserve more mobility,” says John P. Dormans, M.D., chief of Orthopaedic Surgery at The Children’s Hospital of Philadelphia. ”The patient is fitted with an artificial prosthesis to replace the missing lower leg while retaining full knee mobility.”

Limb-sparing procedures are a growing option for very young children with malignant tumors of the extremities because of several advances such as magnetic resonance imaging (MRI) that improve the surgeon’s ability to visualize and access tumors before surgery. Removing only the tumor while sparing the limb is also easier with improved chemotherapy regimens. The drugs shrink tumors so more tissue, bone and muscle can be spared and better mobility can be restored.

”Thirty years ago, it was estimated that 80 percent of patients with bone and soft tissue sarcomas would die, whereas today, 80 percent live,” said Dr. Dormans. ”Additionally, 30 years ago, 80 percent had amputations, and now at least 80-90 percent have limb-sparing surgery.”

Rotationplasty allows for better function than amputation and better durability as the child’s legs continue to grow. A low rate of long-term complications after surgery give it an advantage over other forms of limb salvage, and patients are able to walk mor efficiently.

Eight thousand cases of pediatric cancer are diagnosed in the U.S. each year — bone and soft-tissue sarcomas make up 11 percent of this total (880 cases per year). Six hundred children die of cancer each year making cancer the most common cause of death from disease in childhood and adolescence. Osteogenic sarcoma (osteosarcoma) is the most common malignant bone tumor of childhood; Ewing’s sarcoma is the second most common.